Ms. Farrar and her fellow researchers seem to have missed Dr.
Hutchon's principal argument - that cord closure is a physiological event;
the most basic tenet of all medical care is the preservation or
restoration of physiology. Their research is based on two false premises:
1. that the cord should be clamped (physiology should be disrupted),
and
2. that there is an optimal time to inflict this injury.
Research on physiological cord closure [1] shows that increase in
oxygen tension in umbilical arterial blood (lung ventilation) causes
release of prostaglandin from the arterial walls - which constricts and
closes the umbilical arteries, the ductus arteriosus and the ductus
venosus. Transfer of prostaglandin to the maternal circulation would also
constrict the uterus. This exquisite mechanism maintains placental
respiration until pulmonary function and the adult circulation are
established, then terminates placental function. Erasmus Darwin's dictum
of "tying the cord after repeated breathing and after cord pulsation has
ceased" would not prevent prostaglandin release. The research [1] also
shows that prostaglandin does not close the umbilical vein, indicating
that placental transfusion could still be occurring at the time of
Erasmus' clamp.
The relationship of early or late clamping to post-partum blood loss
thus depends on whether the child breathed before or after the early or
late clamp was applied. Not surprisingly, Ms. Farrer and colleagues' fallacious concept
of "optimal timing" produces "unclear" results, and could enhance
persistent fetal circulation. Clamping at any time will not improve the
physiological mechanism.
There are no "conflicting recommendations" on the "substantive
clinical outcome" of infant anemia; immediate clamping is causative, [2]
and the degree of infant anemia (Hbg) predicts the degree of mental
retardation (IQ) at age 10 years. Low birth weight anemic infants develop
even lower IQ's.[3]
Similarly, resuscitated infants (resuscitation entails immediate cord
clamping and removal to a resuscitation table) had an increased risk of
mental retardation (IQ < 80) [4]
Ms Farrar and colleagues have no evidence at all that her experiments with cord
clamps are beneficial in any way, or improve on physiology. If
physiological closure (clamping AFTER placental delivery - see Cord
Clamping: No Further Research Needed above) were practiced on every birth
(all gestational ages) in one or two hospitals for two months, the NICU's
would empty. This "rush to change" is indicated immediately.
References:
1. J C McGrath, S J MacLennan, A C Mann, K Stuart-Smith. Contraction of
human umbilical artery, but not vein, by oxygen. J. Physiol. 1986;380;513
-519
2. Hutton EK, Hassan ES. Late vs Early Clamping of the Umbilical
Cord in Full-term Neonates. JAMA, March 21, 2007--Vol 297, No. 11 1241-
1252
3. Hurtado EK et al. Early childhood anemia and mild to moderate
mental retardation. Am J Clin Nut. 1999; 69(1): 115-9.
4. Odd DE, Lewis G, Whitelaw A, Gunnell D. Resuscitation at birth and
cognition at 8 years of age: a cohort study. www.thelancet.com . Published
online April 21, 2009 DOI:10.1016/S0140-6736(09)60244-0
Rapid Response:
Re:More evidence needed to inform practice
Ms. Farrar and her fellow researchers seem to have missed Dr.
Hutchon's principal argument - that cord closure is a physiological event;
the most basic tenet of all medical care is the preservation or
restoration of physiology. Their research is based on two false premises:
1. that the cord should be clamped (physiology should be disrupted),
and
2. that there is an optimal time to inflict this injury.
Research on physiological cord closure [1] shows that increase in
oxygen tension in umbilical arterial blood (lung ventilation) causes
release of prostaglandin from the arterial walls - which constricts and
closes the umbilical arteries, the ductus arteriosus and the ductus
venosus. Transfer of prostaglandin to the maternal circulation would also
constrict the uterus. This exquisite mechanism maintains placental
respiration until pulmonary function and the adult circulation are
established, then terminates placental function. Erasmus Darwin's dictum
of "tying the cord after repeated breathing and after cord pulsation has
ceased" would not prevent prostaglandin release. The research [1] also
shows that prostaglandin does not close the umbilical vein, indicating
that placental transfusion could still be occurring at the time of
Erasmus' clamp.
The relationship of early or late clamping to post-partum blood loss
thus depends on whether the child breathed before or after the early or
late clamp was applied. Not surprisingly, Ms. Farrer and colleagues' fallacious concept
of "optimal timing" produces "unclear" results, and could enhance
persistent fetal circulation. Clamping at any time will not improve the
physiological mechanism.
There are no "conflicting recommendations" on the "substantive
clinical outcome" of infant anemia; immediate clamping is causative, [2]
and the degree of infant anemia (Hbg) predicts the degree of mental
retardation (IQ) at age 10 years. Low birth weight anemic infants develop
even lower IQ's.[3]
Similarly, resuscitated infants (resuscitation entails immediate cord
clamping and removal to a resuscitation table) had an increased risk of
mental retardation (IQ < 80) [4]
Ms Farrar and colleagues have no evidence at all that her experiments with cord
clamps are beneficial in any way, or improve on physiology. If
physiological closure (clamping AFTER placental delivery - see Cord
Clamping: No Further Research Needed above) were practiced on every birth
(all gestational ages) in one or two hospitals for two months, the NICU's
would empty. This "rush to change" is indicated immediately.
References:
1. J C McGrath, S J MacLennan, A C Mann, K Stuart-Smith. Contraction of
human umbilical artery, but not vein, by oxygen. J. Physiol. 1986;380;513
-519
2. Hutton EK, Hassan ES. Late vs Early Clamping of the Umbilical
Cord in Full-term Neonates. JAMA, March 21, 2007--Vol 297, No. 11 1241-
1252
3. Hurtado EK et al. Early childhood anemia and mild to moderate
mental retardation. Am J Clin Nut. 1999; 69(1): 115-9.
4. Odd DE, Lewis G, Whitelaw A, Gunnell D. Resuscitation at birth and
cognition at 8 years of age: a cohort study. www.thelancet.com . Published
online April 21, 2009 DOI:10.1016/S0140-6736(09)60244-0
G. M. Morley, MD FACOG
obgmmorley@aol.com
Competing interests: No competing interests